The NFL explains:
In addition to being notified that Terrelle Pryor may be selected in the Supplemental Draft, NFL clubs were informed that Pryor made decisions that undermine the integrity of the eligibility rules for the NFL Draft. Those actions included failing to cooperate with the NCAA and hiring an agent in violation of NCAA rules. This resulted in Ohio State declaring him ineligible to continue playing college football. Pryor then applied to enter the NFL after the regular draft. Pryor had accepted at the end of the 2010 college football season a suspension for the first five games of the 2011 season for violating NCAA rules.Deadspin finds this "incredible" and perhaps it will not stand if Pryor sues and/or the NFLPA gets involved.
In his decision allowing Pryor to enter the Supplemental Draft, Commissioner Roger Goodell determined that Pryor will be ineligible to practice prior to or play in the first five games of the NFL regular season after he signs. Pryor may be selected in the Supplemental Draft, negotiate and sign a contract with an NFL club, and fully participate in the remainder of the preseason.
But consider: At least part of the problem with NCAA enforcement is that the real wrongdoers (and let's assume for the moment that NCAA regs are worth enforcing and those who break those rules are worthy of sanction) virtually never are punished. The players and coaches involved in the misconduct are long gone from a school by the time any punishment is imposed and the punishment falls entirely on a new coach and new players who had nothing to do with anything. For the players who are just marking time in college because they have to, having to leave college and jump into the pros (as Pryor is doing) is not a meaningful sanction.
The answer thus is for the pro leagues to enact their own rules sanctioning professional players who broke NCAA rules. This is particularly so, as with Pryor, the wrongdoing was a direct step to trying to go into the pros (or so the NFL believes) and the wrongdoing is close in time (as opposed to the wrongdoing being discovered three years into the player's NFL career, as with, for example, Reggie Bush).
The question, beside whether this will work, is whether this is a one-shot deal or the NFL is serious about trying to bolster NCAA enforcement by wielding its own punishment authority.